The objectives of this research are: division of the process of transcription into discrete chemical steps with measurable parameters; delineation of the extent and nature of the participation of each subunit of the RNA polymerase in each of these steps; identification of active sites formed within between or among subunits and measurement of the effects of alteration of structure of the subunits on each step. The specific aims of this research are: 1) Characterization of mutant bacterial RNA polymerases to permit identification of the enzymatic step or steps affected in each mutant and to permit definition of biochemical steps in RNA synthesis. 2) Identification of the subunit of RNA polymerase affected in each mutant. 3) Reversion studies to permit correlation of genetic and biochemical observations.